1. Field of the Invention
The present invention relates to toggle or over-center latches, and particularly though not exclusively to toggle latches used for joining together the leaves of extendable table tops.
2. Description of the Prior Art
Toggle latches are well known in the art, and are often used for locking cases, such as suitcases.
A toggle latch generally comprises a base plate, a lever body pivotally mounted on the base plate, a sprung claw pivotally carried on the lever body, and a separate curved latch plate. The latch plate is fitted to the edge of one case half, and the base plate assembly is fitted to an opposing edge of the other case half.
The latch is latched by pivoting the lever body up and forward towards the latch plate so that the claw passes over the curved portion of the latch plate. The lever body is then pivoted back from the latch plate and pushed down to its home position flat against the case. This causes the claw to be drawn against and hooked by the curved portion of the latch plate. As the lever body is pushed down, the claw is put into tension, and the end of the claw which is mounted on the lever body is moved past an over-center position. On moving past the over-center position, the tension in the claw urges the lever body to rotate about its pivot point towards the base plate, thereby pulling the latch plate and the lever body together and urging the lever body into its home position flat against the case. This action causes the case halves to close firmly together.
To release the latch, the lever body is pivoted upwards against the tension in the claw, past the over-center position, and towards the latch plate, so that the claw becomes loose. The claw may then be easily disengaged from the latch plate, and the case may be opened.
Such latches are not only used for locking cases, and may be used in many different situations. In one particular use with which the present invention is particularly concerned, a number of latches are mounted on the underside of the leaves of an extendable table top, along the edges where the leaves abut one another, to fasten the leaves firmly together.
Such toggle latches are simple, compact and work well. The inventor of the present invention, however, has identified a problem with them in that, when in the unfastened condition, the claw (and usually also the lever body) hang loose. This is not necessarily a problem with for example cases, as these are usually kept closed with the latches latched. However, problems can occur when the latches are used with for example table top leaves, as the additional leaves for extending the table will for most of the time be stored away, with the latches in their unlatched state. In such situations, the claw and lever body of each latch hang freely from the flat underside of the leaves, and may cause scratching and other damage, with the possibility of catching on other objects.